* Added `LootOwner` component used to indicate that an `ItemDrop` entity is owned by another entity
* A loot winner is now calculated after EXP allocation using the EXP per entity for weighted chance distribution
* Used existing Inventory Full overitem text to show "Owned by {player} for {seconds}secs" when a pickup fails due to a loot ownership check
* Updated agent code to take into account loot ownership when searching for `ItemDrop` targets to pick up
* Added `loot` ECS system to clear expired loot ownerships
